Heat treatment apparatus



"J. SCHONBRUNN ET AL HEAT TREATMENT APPARATUS Filed Sept. 8, 1927 2Sheets-Sheet 1 72167076 '@bzz%e5 ladle,

a 661 mm Jan. 1, 1929.

J. SCHONBRUNN ET AL HEAT TREATMENT APPARATUS Filed Sept. 8, 1927 2Sheets-Sheet 2 Patented Jan. 1', 1929 UNITED STATES JAKOB SGHONBBUNN, orAABAU, AND Go'r'rLIEB KELLER, or BRUGG, SWITZERLAND,

nssrenons T0 AKTIENGESELLSCHAFT BROWN novnnr & era, 01* BADEN, swI'rzEE-LAND, A JOINT-STOCK COMPANY or SWITZERLAND.

7 HEAT TREATMENT APPA ATUS.

Application filed September 8, 1927, Serial 2N0.

This invention relates to heat treatment apparatus, particularlyfurnaces such as may be employed for annealing or other heat treatmentsof various materials.

The general object is the provision of a furnace apparatus which isadapted to increase production byvirtue of provision of means forexpediting the cooling of a charge while itis still within the furnaceand protected from undesirable efiects of atmosphere, dust,contam'inatiorQ, or the like.

Another object is the provision of an apparatus which is adapted toexpedite and regulate cooling of a charge in the furnace withoutinvolving excessive loss of heat in subsequent heating of a succeedingcharge.

A further object is the provision of apparatus having thecharacteristics specified which may be easily and rapidly operated toaccommodate charging and discharging and WhlCll expedites coohng andheating of charges. 1

Other and further objects will be pointed out or indicated hereinafter,or Will appear to one skilled in the-art upon an understanding of theinvention or its employment in practice.

In the drawing forming a part of this specification we illustrate threestructural embodiments of the invention but it is to be understood thatthese are presented for purpose of illustration only and are not to beaccorded any interpretation calculated to limit the claims short of thetrue and most comprehensive scope ofthe invention in the art.

In said drawings, u

Fig. 1 is a sectional elevation, shown diagrammatically, of one form ofapparatus cover is provided with an elevating mechaembodying theinvention, the furnace being in the closed condition, as fpr heating ofa charge;

Fig. 2 is a similar diagrammatic sectional elevation representing thefurnace in con dition for cooling of a charge therein;

Fig. 3 is a similar sectional elevation of a,

second embodiment of the invention, the furnace being shown in thecondition when closed for heating of a charge; and' Fig. 4 is asectional elevation of a third embodiment of the invention with thefurnace closed for the heating of a charge.

Certain heattreatment processes require that the cooling down of thecharge should 218,158, and in Germany September 10; .1926.

take place within the furnace itself. For example, if certain metallicarticles are required to be bright (unoxidized) after the heattreatment, care must be taken to exclude all air from them durin theheating and cooling periods. To keep own the heat loss during theheating period, the furnace walls must be made of material having a lowheat conducting capacity, and while ex edit- 1ng heating of a charge,this has the e ect of rendering the cooling period disproportionatelylong, far longerthan is necessary for the requisite cooling down of thecharge The productive ca acityof such' a heat losses will be great, andthe economy under such conditions will be low.

- According to the present invention, the furnace may be well insulated,and the heating costs kept within an economical range, while at the sametime rapid cooling of the charge. may be elfected, with completeexclusion ,of air during heating and cooling.

The nature of the invention will be ascentained from the examplesillustrated in the accompanying drawings. Figs. 1 and 2 represent oneconstruction of apparatus in which the furnace is of pit form having thewalls and'bottom 10 with heat insulating lining 10, and the removablevcover 11 with linin 11. Of course, the walls and cover may madethroughout of material having the necessary heat insulating qualities.The

nism including the sheaves 12 over which run suspension members 14 iwhich carry the cover, the weight of the latter being almost completelycounterbalanced'by the weights 15, so that it may be raised with theappllcation of but little power.v The sheaves may be actuated inslillitable fashion to raise the cover to the c argiug position,Suitable heating means, such'as the electricalheating elements 16, areprovided for heating the furnace chamber mteriorly, and the furnace maybe rendered gas tight by enclosing its walls and bottom with a metalshell 17. A pipe 18 is provided throughwhich an'inert 'gas may besupplied to the furnace under 7 rounded by a chamber 22 formed byenclosing the furnace within a tank 24, said chamber being adapted tohold liquid, such as water, which may be introduced through a pipe 25,to fill the chamber to the overflow 26. A

suitable valve control 27 is arranged to per mit discharge of the liquidfrom the chamber 22. The movable cover carries a bell 28 which hasrelatively thin walls made of material having good heat conductivity andadapted to move in telescopic relationship with the walls of thefurnace, completely encompassing the same, said bell adapted to travelin'the chamber 22, and carrying at its lower end a float 29, arranged topermit the lower margin of the bell 28 to dip below the surface of theliquid in the chamber 22 to an extent sufficient to fornran effectiveair seal. The float has suflicient buoyancy to support the difference inweight between the cover and bell on the one hand and the counterweights15 on the other hand, so that the cover and bell may be elevated byliquid introduced into the sealing chamber 22. I

In operation, the cover, together with the bell, is elevated to asuflicient extent to permit the charge to be introduced into the furnacechamber and the cover is lowered to the position illustrated in Fig. 1,the sealing chamber 22 being nearly empty of liquid to permit this, Thefurnace chamber is filled with the inert gaging-ress of air beingprevented by the seal afforded by the liquid in which the lower end ofthe bell is submerged. The heat is then applied and the charge broughtto the requisite temperature. Then,

. for the cooling down of the charge, liquid is introduced through thepipe 25 into the sealing chamber 22, resulting in't he elevation ofthecover and the bell to a position such as illustrated in Fig. 2, whereinthe gas enclosed within the furnace chamber and the bell, which nowformssubstantially an extension of the furnace chamber, is exposed to thecooling effect of the bell, the walls of which are relatively thin andof good heat conducting material and are cooled exteriorly. Thus thecharge may be cooled much more rapidly than would be possible by thenormal progress of radiation through the poorly conducting walls of thefurnace. At the same time, ingress of air is prevented, so that thecharge may be cooled to the proper degree without exposure to oxidationor dust or other contamlnating influences outside the furnace.

When the charge is sufficiently cooled, the confined inert gas may bewithdrawn through pipe-20, and the cover and bell then elevated to theposition permitting discharge and recharging of the furnace. I Whenagain closed, the furnace and the new charge may be heated quickly tothe desired temperature without undue loss of heat through the furnacewalls. Thus, it will be observed, the output of the furnace may begreatly increased due to the shortening of the heating and cooling downperiods.

In the embodiment illustrated in Fig. 3, the movable cover 11 is adaptedto close the sealing chamber 22 as well as the furnace chamber, thuscontributing to the heat insu-' lation of the furnace during the heatingperiod, the encompassing walls 24' in this lnstance being made also ofmaterial of low heat condiictivity. The other parts shown in thisembodiment are as described in reference to the form shown in Figs. 1and 2, and operate in similar fashion. By the provisions ilustrated inthis embodiment, the furnace chamber walls may be less massive than nor-0 Inally required, and the time necessary for coolingthereby stillfurther reduced. The cooling may be expedited by using the sealingliquid also as a cooling medium, by passing it continuously into and outof the sealing chamber during the cooling period.

A third embodiment is illustrated in Fig. 1 4, wherein the furnacechamber walls are comparatively thin, to facilitate the escape of heatduring the cooling period, the insulating effect during the heatingperiod being contributed by the downward extensions 11 of the cover,which extensions encompass the furnace chamber walls when the cover isin the closed position. The bell28 is formed as an extension from thelower end ofthis cover skirt and has thin walls of good heat the loweredposition. The accessories forv the embodiments illustrated in Figs. 3and 4 may be the same as in Figs. 1 and 2, and the operation issubstantially the same.

What We claim is: v

1. Heat treatment apparatus comprising the combination of a furnacechamber, means for heating the same interiorly, a movable closure forthe chamber, and a heat-conductive extension carried by the closure andmovable therewith to maintain the chamber closed to atmosphere when othecover is removed therefrom.

2. Heat treatment apparatus comprising the combination. of aheat-insulated furnace chamber, means for heating the same interiorly, aheat-insulating movable closure for the chamber, and aheat-conductingclosure I portion movable into exposure to the atmospheres inside andoutside the furnace chamchamber and to support the former in a se- 65ber to' f a cilitate transfer of heat between them.

3. Heat treatment apparatus comprising the combination of aheat-insulated furnace chamber, and a closure for same comprising aheat-insulating portion and a heat conducting portion, said closurebeing movable to a position wherein the chamber is closed by theheat-insulating portion and to another position wherein the confinedatmosphere is exposed to the heat-conducting portion.

4. In heat treatment apparatus, the combination of a heat-insulatedfurnace chamber, means for heating the chamber interiorly,

a movable cldsure for the chamber, a heatconducting shell movable withsaid closure in telescopic relationship with the chamber, and means forproviding a seal between the shell and chamber for prevention of ingressof external atmosphereinto the latter.

5. In heat treatment apparatus, the combination of a heat-insulatedchamber, a heat insulated closure therefor, an extension member intelescopic relationship to the chamber and movable with the closure,said extension member being of heat-transmittin material, and means formaintaining a sea between the extension member and the chamber incidentto its movement, to prevent ingress of air into the chamber.

--extension of the chamber, and means coop- 6.'In heat treatmentapparatus, the combination of a heat-insulated chamber, means forheating the same interiorly, a movable closure for the chamber, aheat-transmitting member movable with the closure to form an erativewiththe heat-transmitting member to prevent ingress of air into the chamber.

7. In heat treatment apparatus, the combination of a heat-insulatedchamber, means for heating the same interiorly, a heat-transmittingmember adapted to form an extension of the chamber, a movable closurefor cooperation with the chamber and heat-transmit ting member, andmeans for moving the closure to expose the heat-transmitting. member tothe internal atmosphere of the chamber.

8. In heat treatment apparatus, the combination of a heat-insulatedchamber, a heattransmitting bell adapted to form an extension of thefurnace chamber, a closure for closing both the chamber and bell toprevent ingress of air into the chamber, and means for supporting theheat-transmitting member at a selected position with respect tov thechamber.

10. Heat treatment apparatus as specified in claim 8,'wherein'a liquidis employed to form a seal between the bell and the furnace lertedosition with respect to the latter.

11. eat treatment apparatus as specified in claim 8, wherein a liquid isutilized to form a seal between the bell and the furnace I chamber, thebell being buoyantly supported by the liquid and the height of thelatter determining the position of the bell.

. 12. Heat treatment apparatus as specified in claim 6, together withmeans for introducing an inert atmosphere into the chamber.

13.- Heat treatment apparatus as specified in claim8, together withmeans for introducing an inert gas into the chamber.

14. Heat treatment apparatus as specified in claim/'8, whereintheclosure and bell are movable vertically, together with means forcounterbalancing the weight .of the closure and bell, and .a float forsupporting them bouyantly on the sealing liquid.

15. In heat treatment apparatus, a heatinsulated chamber, a tankenclosing said chamber in spaced relation thereto, a heatinsulatedclosure member for said chamber, and a heat-transmitting member securedto said closure member to provide for" varying the capacity of saidchamber to permit regulation of the rate of cooling thereof.

16. In apparatus of the character described,

means providing a heating chamber, and

rneans'inovable to difierent positions and operable when in one of saidpositions to provide a fluid seal for said chamber and operable when inanother position to provide a cooling chamber for said heating chamberwhile maintaining such seal.

17. In .heat treatment apparatus, a chamber, .a tank disposed about andspaced from said chamber, a closure member provided with an extensiondisposed intermediate said chamber and said tank, and means cooperatingwith said extension td provide therewith a fluid-seal for said chamber.

' 18. Inapparatus of the char "cter described, means providing a heatingch mber, a closure member for said chamber, and means forming part ofsaid closure member and operable when the latter is in positionpartially removed from said chamber to rovide a fluidcooling chamber forsaid heating chamber.

19. In heat treatment apparatus, an insulated closure member for saidchamber, and i a heat-conducting portion depending from said closuremember into the liquid in such wise .as to provide a fluid trap for saidchamber, and means operable to provide a support for said closure memberand said heat-conducting portion and including .float means forming partof said heat-conductmg portion and being responsive to level conditionsof said liquid.

20. In heat treatment apparatus, an insulated chamber, a tank enclosingand spaced from said chamber, the space between said chamber and saidtank being adapted to con- 5 tain a liquid, an insulated closure memberfor said chamber, and a heat-conducting portion depending from saidclosure member into the liquid, said heat-conducting portlon having anannular air chamber formed In the lower portion thereof to buoyantlysup- 1' port said heat-conducting portion.

In testimony whereof We have hereunto subscribed our names this 23 dayof August A. D. '1927, at Zurich, Switzerland.

JAKOB SCHONBRUNN. GOTTLIEB KELLER.

